Measurement of the $${\mathrm {t}\overline{\mathrm {t}}}$$ t t ¯ production cross section, the top quark mass, and the strong coupling constant using dilepton events in pp collisions at $$\sqrt{s}=13\,\text {Te}\text {V} $$ s = 13 Te

Abstract

Abstract A measurement of the top quark–antiquark pair production cross section

$$\sigma _{\mathrm {t}\overline{\mathrm {t}}} $$

σ

t

t ¯

in proton–proton collisions at a centre-of-mass energy of 13

$$\,\text {Te}\text {V}$$

Te

is presented. The data correspond to an integrated luminosity of

$$35.9{\,\text {fb}^{-1}} $$

35.9

fb

- 1

, recorded by the CMS experiment at the CERN LHC in 2016. Dilepton events (

$$\mathrm {e}$$

e

$$^{\pm }$$

±

$$\mathrm {\mu }$$

μ

$$^{{\mp }}$$

∓

,

$$\mathrm {\mu ^+}\mathrm {\mu ^-}$$

μ +

μ -

,

$$\mathrm {e}^+\mathrm {e}^-$$

e

+

e

-

) are selected and the cross section is measured from a likelihood fit. For a top quark mass parameter in the simulation of

$$ m_\mathrm {\mathrm {t}} ^{\mathrm {MC}} = 172.5 \,\text {Ge}\text {V} $$

m

t

MC

= 172.5

Ge

the fit yields a measured cross section

$$\sigma _{\mathrm {t}\overline{\mathrm {t}}} = 803 \pm 2 \,\text {(stat)} \pm 25 \,\text {(syst)} \pm 20 \,\text {(lumi)} \,\text {pb} $$

σ

t

t ¯

= 803 ± 2

(stat) ± 25

(syst) ± 20

(lumi)

pb

, in agreement with the expectation from the standard model calculation at next-to-next-to-leading order. A simultaneous fit of the cross section and the top quark mass parameter in the powheg simulation is performed. The measured value of

$$m_\mathrm {\mathrm {t}} ^{\mathrm {MC}} = 172.33 \pm 0.14 \,\text {(stat)} \,^{+0.66}_{-0.72} \,\text {(syst)} \,\text {Ge}\text {V} $$

m

t

MC

= 172.33 ± 0.14

(stat)

- 0.72

+ 0.66

(syst)

Ge

is in good agreement with previous measurements. The resulting cross section is used, together with the theoretical prediction, to determine the top quark mass and to extract a value of the strong coupling constant with different sets of parton distribution functions.